1. Field of the Invention
The present invention relates to an exposure system, a method of testing an exposure apparatus, and a method of manufacturing a device.
2. Description of the Related Art
In recent years, to keep up with advances in micropatterning and an increase in packing density of semiconductor integrated circuits such as an IC and an LSI and liquid crystal display panels, exposure apparatuses for manufacturing such products have become more accurate and sophisticated. Exposure apparatuses called a stepper and scanner are commonly used in the process of manufacturing such products. These exposure apparatuses sequentially transfer a pattern formed on an original (e.g., a reticle) to a plurality of portions on a substrate (e.g., a wafer) while moving the substrate in steps. An apparatus that performs this transfer by full-field exposure is called a stepper, whereas one that performs this transfer while scanning stages is called a scanner. An exposure apparatus including two substrate stages which hold substrates has recently been put into practical use to meet two demands for improvements in both the overlay accuracy and throughput which are of prime importance for exposure apparatuses. In addition, the development of an exposure apparatus which attains high-resolution transfer by filling the space between a substrate and a projection optical system which projects an image of an original with a liquid has also progressed.
Amid such improvements in accuracy and performance of exposure apparatuses, control software for controlling an exposure apparatus is upgraded as needed so that it becomes more accurate and sophisticated as well. Such control software upgrading is often applicable not only to an exposure apparatus to be newly developed but also to an exposure apparatus that has already been put into operation. Control software version upgrading for updating the control software installed on an active exposure apparatus to new control software is frequently performed.
Conventional control software version upgrading in an exposure apparatus will be described next. FIG. 7 is a schematic block diagram showing an exposure system that updates the control software installed on an exposure apparatus to new control software. A semiconductor device manufacturing plant 1 as one example of the installation location of an exposure apparatus is equipped with an exposure apparatus 11 and an updating unit 15 that updates control software. The exposure apparatus 11 includes an exposure unit 12 which exposes a substrate via the pattern of an original, a controller 13 which controls an exposure apparatus, and a data holding unit 14 which holds control software used to control the exposure apparatus. The updating unit 15 is connected to one or more exposure apparatuses 11 and updates the control software on the exposure apparatus 11 to new control software.
FIG. 8 illustrates one example of the procedure for updating the control software on an exposure apparatus. In step S801, the updating unit 15 inspects the hardware configuration and necessary functions of an exposure apparatus having its control software to be updated, and determines the version of control software to be adopted. In step S802, the operator prepares a medium that stores new control software necessary for updating, and copies it into the updating unit 15. More specifically, the operator inserts a medium such as a magnetooptical disk that stores new control software into the updating unit 15, and copies the new control software and its associated data such as an installer into the updating unit 15. After executing steps S801 and S802 in advance, the operator stops the exposure process of the exposure apparatus 11 in step S803.
In step S804, the updating unit 15 updates the control software on the exposure apparatus. More specifically, using data containing the control software stored in step S802, the updating unit 15 updates the control software stored in the data holding unit 14 of the exposure apparatus 11. By restarting the controller 13 and exposure unit 12 of the exposure apparatus 11 after the control software is updated, the updated software is reflected on the exposure apparatus 11. Lastly, in step S805, the exposure apparatus 11 after its control software is updated is tested. If no problem is found in the test in step S805, the exposure apparatus 11 starts an exposure process in step S806. Note that in step S805, the exposure apparatus 11 performs, for example, test exposure in order to confirm that the control software has been updated correctly.
Japanese Patent Laid-Open No. 11-296352 discloses an example of such updating of the control software on an exposure apparatus. In this example, the control software on an exposure apparatus is updated by confirming the remaining memory capacity of an external storage device which stores, for example, control software. Updating the control software on an exposure apparatus makes it possible to improve the accuracy and performance of even an active exposure apparatus, and this is effective in improving the productivity of the exposure apparatus.
In the development of control software for an exposure apparatus, control software tests are frequently conducted every time a new version is created to keep up with frequent version upgrading. To conduct these control software tests, it is a common practice to confirm the operation of the control software by an exposure apparatus. In contrast, Japanese Patent Laid-Open No. 11-186118 proposes a method of confirming the operation of the control software using a device (to be referred to as a simulator hereinafter) that simulates the operation of an exposure apparatus. The use of a simulator allows an efficient test operation and prevention of any damage inflicted on the exposure apparatus by the control software during the test.
As has been described above, to improve the productivity of an active exposure apparatus, it is effective to improve the accuracy and performance of the exposure apparatus by control software updating.
As has been described in “Description of the Related Art”, control software for controlling an exposure apparatus has become more sophisticated. In response to this trend, the function of the control software has become more complex. An exposure apparatus has a multiple of options, so a multiple of functions are imparted to control software especially for an exposure apparatus in correspondence with these options. An exposure apparatus has, for example, an option for selecting exposure light in accordance with the user's purposes, and an option for selecting the position to load a substrate into the apparatus in accordance with the installation location of the apparatus, and functions corresponding to these options are imparted to control software for an exposure apparatus. Also, control software itself has an option for speeding up the processing involved by optimizing the control method adopted in accordance with the user's application. Control software becomes larger with its increasing complexity, so it is a mainstream practice to control an exposure apparatus by a combination of a plurality of software programs. Under the circumstance, the number of necessary software programs increases as well.
Control software for an exposure apparatus is generally developed and tested by a vendor as the developer of the exposure apparatus. As described above, as control software becomes more complex and larger, both the cost of development of control software and that (e.g., the test time) of a test of the control software rise. Especially various types of hardware and software options and test items as a combination of various types of increasing functions and various types of software for controlling an exposure apparatus reach huge numbers, and this raises the test cost of control software. To combat this situation, it is possible to improve the efficiency of a test of control software by exploiting the method that uses a simulator, described in “Description of the Related Art”, but a demand has arisen for a method of further improving the efficiency of a test.
Since an exposure apparatus is a production facility, it is generally used without interruption all day. Hence, the downtime as the time for which an exposure apparatus is used for purposes other than an exposure process, such as maintenance, adversely affects the user productivity. Although control software updating is effective in improving the productivity in the long run, the exposure apparatus must be stopped during the control software updating, and this temporarily lowers the productivity. If a test of control software to be updated is unsatisfactory, updating may fail or the updated control software may damage the exposure apparatus. When this occurs, an operation such as returning of the control software version to old one must be performed, and this more largely lowers the user productivity.
Since an exposure apparatus is a manufacturing apparatus, it has an aspect of being used only to manufacture specific products. Also, manufacturing plants which use exposure apparatuses are generally large-scale, and the number of them is naturally limited. Due to these facts, exposure apparatuses are used at limited locations by limited methods in practice as compared with general products. That is, an exposure apparatus has enormous amounts of combinations of options and functions but the combinations used in practice are limited to specific ones.
The optical performance and other performances of a projection optical system of an exposure apparatus temporally change, so even individual exposure apparatuses of the same model have differences in state. When the control software on an exposure apparatus is updated with no concern for the state of the exposure apparatus attributed to this temporal change, updating may fail or the updated control software may damage the exposure apparatus.